1. Field of the Invention
This invention relates to an imaging apparatus and an imaging method for imaging a biological sample carried in a sample container.
2. Description of the Related Art
In medical or bio-scientific experiments, biological samples such as specimen tissues extracted from biological bodies or cells cultured in liquids or gel-like media are observed and measured. Conventionally, it has been a general practice to stain a biological sample with an appropriate dye matching an imaging purpose and image the biological sample with enhanced visibility. However, to avoid damage to a sample, the sample needs to be imaged without being stained in some cases. A configuration example of an imaging apparatus for such a purpose is disclosed in JP2013-072684A. In the imaging apparatus disclosed in this literature, illumination light is incident on a sample such as cells cultured in a recess (well) formed in a microplate from a light source arranged above the sample. The light transmitted downward through the sample is received by a line sensor and thus a two-dimensional image of the sample is imaged by the scanning of the line sensor.
The apparatus disclosed in the above literature is suitable for imaging a thick imaging object such as a cell cluster three-dimensionally cultured in a relatively deep well. On the other hand, in imaging, for example, cells or the like cultured by adhesion culture on an inner bottom surface of a container as an imaging object, a good image may not be obtained. This is because light incident on the cells or the like mostly transmits to reduce a change in the quantity of the transmitted light caused by the presence or absence of the cells or the like and it is difficult to obtain a high image contrast since the sample is thin.
To solve this problem, it is considered to increase or decrease a light quantity of illumination light by a diaphragm and apply a dark field imaging technology. However, in these cases, it may become difficult to observe the structure and the like of an imaging object due to insufficient brightness of an image. Thus, it is desired to establish an imaging technology capable of providing a good image contrast by a simple method even if an imaging object is relatively thin.